Flocking is a special technology intended to coat a surface decoratively. This technology allows applying fibres by fixing them to a support material that has previously been coated with an adhesive. To do this, an adhesive is applied on a support, over which adhesive layer short fibres called flock are projected in order to form a flock layer.
The use of flock coatings is known for application in inner vehicle parts, particularly in automotive vehicles, such as sunshades, pillars, roof, door and seat trimmings, for example. One example is German patent document DE 3622263.
These coatings can be applied mainly in two ways, by flocking a support the configuration of which has two dominant dimensions for its subsequent application on a formed workpiece, called two-dimensional flocking, or by its direct application upon the surface of a three-dimensional workpiece, called three-dimensional flocking.
In the first case, we start from a two-dimensional laminated support, a textile support for example, to which an adhesive layer is applied. Subsequently, by means of an electrostatic flocking process consisting in projecting the fibres forming the flock layer onto an adhesive layer through an electrostatic field so as to make them all face the same direction, for example, these fibres are distributed with an orientation that is perpendicular to the support.
Finally, the adhesive is subjected to a drying process and the flock surface is cleaned in order to eliminate any fibres that are not properly adhered to the adhesive.
Once the flock support is obtained, a textile support, for example, it is used to coat a formed workpiece or a workpiece is formed at the same time in order to obtain a final workpiece.
Another way to apply the flock is by applying the adhesive layer directly on the three-dimensional workpiece in order to subsequently project the fibres on said layer, which is called three-dimensional flocking. In this case, the support is the formed workpiece itself.
The application of indicative and/or decorative motifs on this type of flock coatings can be achieved for example by modifying the colour of the fibres applied by dying them prior to their application.
Another way of applying motifs can be by the use of fibres with different geometric characteristics, or the localised application of such fibres on the support, copying the design of the motif to be represented on the support.
Another technique that is known in order to apply motifs on flock coatings consists in engraving the motifs by the action of a laser beam that melts part of the fibres forming the flock, producing different tones between the area on which laser beam has acted and where it has not.
In this case, the effect produced by the different tones obtained is limited by the original colour of the fibres forming the flock support, since the laser beam can only darken the colours by melting the fibres present in the support with its heat. Therefore, in this case the effect obtained is limited to the different tones that can be obtained from a single colour, produced by the variation of the heat applied on said fibres.
There are solutions known in the state of the art to achieve this differentiation effect between the colours of the engraved motif, which consist in the use of a two-layer element made up of an outer or upper layer and an inner or lower layer, such that the colour of the lower layer is different to that of the higher layer.
Thus, the application of a laser beam on the outer or upper layer causes the elimination of part of the material of said upper layer, such that it reveals the lower layer, producing a two-colour effect that allows representing a motif with a specific design. An example of this technique is found in document U.S. Pat. No. 6,633,019.
In this case it is necessary to use an additional layer with a different colour to that of the outer layer of the support, thus achieving the two-colour effect.
The object of the invention is therefore to engrave an indicative and/or decorative motif on an inner flock coating by the action of a laser beam thereupon, producing on said coating at least two areas that can be differentiated by the human eye due to characteristics such as colour, photoluminescence, etc., for example, without having to use additional layers as part of said coating.